Practice and preparation go hand in hand for the TOEFL test. You can never be over prepared and you can never have too much practice. Taking the IBT test isn't easy. You can only benefit from practicing as much as you can before your test date.
The more you know about the IBT test, the better off you will be. You need to know what it contains, the time it takes, the topics you can expect, the sections, the number of questions, and the type of questions. You need to know what level your English skills in reading, listening, writing and speaking are BEFORE you take the official test so you have time to improve them.
The most practical and price effective method is to do complete practice tests that simulate the real test. Free materials you can find on the Internet, like TestDEN's IBT demo, TOEFL Speaking and Writing Trainer demo, TOEFL Grammar Skills Trainer demo, and our mini TOEFL tests are only a great starting point in your preparation. Books and CD-ROMs are helpful study tools to give you more insight to the IBT test, but it's an online test, it's not done in a book. The experience just doesn't measure up. ETS has their Practice Online Tour which is a bit of a TOEFL guide, includes sample questions and directs you to their other online material, some of it free, some you have to pay to access. There are other online companies that offer a variety of full practice tests.
You should do a practice test as if you were taking the real test. Do your best to get all the questions right. If you do TestDEN's TOEFL tests, you will get a score after completing the test and have access to the review. Going through the review is essential. You can quickly see which questions types you're having trouble with. Reading the explanation will help you understand why you got it wrong. After some more practice, you should try doing one or more full tests to see how well you've improved.
When you take the official test, you get your score, but that's about it. The score report won't show all the questions you got wrong and what the correct answers are. If you need to take the test again, you won't necessarily know what specific skills you need help with. A tutor or taking a course, although it's expensive, might be a better option than to continue practicing on your own.
Even if you're feeling good about your English skills, there's always something you can improve on. Are you aware you will take the IBT test on a computer with a QWERTY keyboard? It's the type of keyboard used in North America and differs from those used in some countries. Not being familiar with one come test day might be frustrating or throw your concentration off.
With all your practice and hard work to prepare for the test, don't forget to go over the ETS requirements of what you need for test day, like your ID. And as important as practice is, remember to have some fun and rest. There's even educational games so you can combine learning and fun.